Not a good choice for gaming. HD 3450 and HD 3650 are built for smooth HD playback and other desktop oriented GPU tasks. I think the primary difference between the two is that HD 3650 is better suited for dual monitors, while HD 3450 is sufficient for a single monitor.
Either way, those cards aren't meant for gaming and thus not in the same league of 8800's. 8600's might fare better in gaming but there isn't really a point to getting a 8600 at this point, IMO. You can have a 8800 GS under $100 if you're into gaming. Otherwise, a HD 3450 for ~$40 is an excellent deal.